We have rationally designed the leflunomide metabolite analog alpha-cyano-beta-hydroxy-beta-methyl-N-(2,5-dibromophenyl)-propenamide (LFM-A13) as a specific inhibitor of the protein tyrosine kinase, Bruton's tyrosine kinase (BTK). LFM-A13 is a chemosensitizing anti-leukemic agent with anti-thrombotic properties. Our preclinical studies established that LFM-A13 has a favorable safety and pharmacokinetics profile. LFM-A13 has been formulated for oral administration (LFM-A13-F). Under SPECIFIC AIM 1, we will study the toxicity profile of LFM-A13-F in rats and dogs and 2) synthesize and formulate large quantities of LFM-A13 under GMP conditions to be used for human clinical trials. Based on the toxicity studies done in mice, we hypothesize that LFM-A13-F will not cause acute, subacute, or chronic toxicity at the proposed dose levels. Under SPECIFIC AIM 2, large scale synthesis and evaluation of LFM-A13-F as hard gelatin capsules will be carried under Good Manufacturing Practice (GMP) to comply with FDA regulations and to ensure preparation of clinical grade LFM-A13-F for human clinical trials. We will use synthetic procedures developed during the phase I studies. In order to achieve specific aim 2 we have already identified FDA approved facilities for the synthesis and formulation of LFM-A13. The results obtained in specific aim #1 and specific aim #2 will provide the critical information for further testing of this agent in human subjects under Phase III. This research will facilitate the bench-to-bedside development of LFM-A13 as the protype of a new class of anti-leukemic agents with anti-thrombotic properties.